HP StoreOnce Backup System Concepts and Configuration Guidelines (BB877-90913, November 2013)

by creating media pools with the backup application then manually assigning source library
cartridges into the relevant pools. For example the backup administrator may configure 3 pools:
• Daily Incremental, 5 cartridge slots (overwritten each week)
• Weekly Full, 4 cartridge slots (overwritten every 4 weeks)
• Monthly Full, 12 cartridge slots (overwritten yearly)
Replicating only the slots that will contain full backup cartridges saves five slots on the replication
target device which could be better utilized to accept replication from another source library.
NOTE: The Catalyst equivalent of this requires the actual Backup policies to define which backups
to Catalyst stores are to be copied and which are not – so for example, you could configure only
Full backups to be copied to Catalyst stores.
Appliance library and share replication fan in/fan out
Each StoreOnce model has a different level of support for the number of other StoreOnce appliances
that can be involved in replication mappings with it and also the number of libraries that may
replicate into a single library on the device. The configuration settings are defined below.
The maximum number of target appliances that a source appliance can be paired withMax Appliance Fan Out
The maximum number of source appliances that a target appliance can be paired withMax Appliance Fan In
The maximum number of target libraries that may be replicated into from a single source
library on this type of appliance
Max Library Fan Out
The maximum number of source libraries that may replicate into a single target library
on this type of appliance
Max Library Fan In
The maximum number of target NAS Shares that may be replicated into from a single
source NAS Share on this type of appliance
Max Share Fan Out
The maximum number of source NAS Shares that may replicate into a single target NAS
Share on this type of appliance
Max Share Fan In
It is important to note that when utilizing a VTL replication Fan-in model (where multiple source
libraries are replicated to a single target library), the deduplication ratio may be better than is
achieved by each individual source library due to the deduplication across all of the data in the
single target library. However, over a large period of time the performance of this solution will be
slower than configuring individual target libraries because the deduplication stores will be larger
and therefore require more processing for each new replication job.
Concurrent replication jobs
Each StoreOnce model has a different maximum number of concurrently running replication jobs
when it is acting as a source or target for replication. When many items are available for replication,
this is the maximum number of jobs that will be running at any one time. As soon as one item has
finished replicating another will start.
For example, an HP 2620 may be replicating up to 4 jobs to a StoreOnce 4430, which may also
be accepting another 44 source items from other StoreOnce systems. But the target concurrency
for a 4430 is 96 so the target is not the bottleneck to replication performance. If total source
replication jobs are greater than 96 then the StoreOnce 4430 will limit replication throughput and
replication jobs will queue until a slot becomes available.
Apparent replication throughput
In characterizing replication performance we use a concept of “apparent throughput”. Since
replication passes only unique data between sites there is a relationship between the speed at
which the unique data is sent and how that relates to the whole backup apparently replicated
82 Replication